Carlos Saavedra (S'92-M'98-SM'05) received the B.Sc. degree in 1993 from the University of Virginia and the M.Sc. and Ph.D. degrees from Cornell University in 1995 and 1998, respectively, all in electrical engineering. From 1998 to 2000 he was a Senior Engineer at Millitech Corporation in South Deerfield, Massachusetts, where he designed 28 GHz and 38 GHz transceiver modules for broadband wireless communication links. In 2000 he joined the Department of Electrical and Computer Engineering (ECE) at Queen´s University, Kingston, Ontario, as an Assistant Professor and was promoted to the rank of Associate Professor in 2006 and to Professor in 2013. He served as ECE Graduate Chair at Queen’s from 2007 to 2010 and has held visiting professorships at different universities while on sabbatical, most recently at the University of Navarra’s School of Engineering (Tecnun) in San Sebastián, Spain.

Dr. Saavedra is a Section Chair of the Natural Sciences and Engineering Research Council of Canada’s (NSERC) Discovery Grants Program Evaluation Group for Electrical and Computer Engineering. He was Chair of the MTT-S Technical Coordinating Committee 22 on Signal Generation and Frequency Conversion from 2010 to 2013 and was guest editor of the September/October 2013 IEEE Microwave Magazine’s Focus Issue “100 Years of Mixer Technology”. He was a member of the Steering Committee and of the Technical Program Committee (TPC) of the 2012 IEEE International Microwave Symposium (IMS) and continues to serve on the TPRC of the IMS. He has served on the TPC of several other conferences, including the IEEE Radio-Frequency Integrated Circuits (RFIC) Symposium, the Asia-Pacific Microwave Conference and the IEEE International Microwave & RF Conference (IMaRC). Professor Saavedra is the author or co-author of 100 peer-reviewed journal and conference papers in his field of research. He is the recipient of an NSERC Discovery Accelerator Award for the period 2011-2014 and is a three-time recipient of the third-year ECE undergraduate teaching award at Queen’s University.

Presentation:

Fundamental and Harmonic Mode Self-Oscillating Mixers

Mixers and their local oscillators are often designed in a modular fashion, meaning that, to a large extent, they are designed as isolated blocks that are eventually interconnected together. On the other hand, if the mixer and its local oscillator are viewed as a unified circuit, some new and interesting design paths emerge. The resulting circuits are usually given the name "self-oscillating mixers," or SOM 's for short. While the majority of SOM 's operate in fundamental mode, there are other SOM 's in which a harmonic mode of the oscillator is used for mixing and this can noticeably increase the operating bandwidth of the SOM. The talk will begin with a review of the origin of SOM mixers followed by some of the key highlights in the evolution of these circuits. A recent trend in SOM design has been to use a Gilbert-cell multiplier as the mixing core together various types of signal generation circuits such as LC-tank oscillators and ring oscillators. New work in SOM 's will be presented in which the oscillator network acts as a double-balanced IF load by stacking the oscillator on top of a low-noise mixer core. The resulting SOM has a minimum DSB noise figure of 4.39 dB at 7.8 GHz. Furthermore, a downconverter SOM that can be reconfigured between fundamental mode and harmonic mode operation will be described. This reconfigurable SOM can function in two distinct RF bands. Applications of SOM 's along with their challenges and limitations will be covered. The talk will conclude with a discussion of future trends.